Various types of known mechanical fasteners comprise matching pairs of fasteners that engage and are held to one another over their surface areas. VELCRO fasteners perhaps are the most commonly known of such type fasteners.
U.S. Pat. No. 5,097,570 of Gershenson, issued Mar. 24, 1992, discloses a fastening system comprising matching fasteners, each having a plurality of alternating flexible burrs and burr receiving cavities. The burrs of one fastener interdigitate with the burr cavities of the other fastener when pressed together. The head of the burrs lock into opposing head cavities formed at the base portion of the burrs of a matching fastener.
U.S. Pat. No. 5,077,870 of Melbye, et al., issued Jan. 7, 1992, discloses a mushroom-type hook-and-loop fastener including an array of upstanding stems, each having a mushroom head. The mushroom heads interlock with corresponding mushroom heads of a matching fastener.
U.S. Pat. No. 4,531,733 of Hall, issued Jul. 30, 1985, discloses, in FIGS. 14A, 14B, a mechanical fastener system comprising matching fastener elements, each including a substrate with a plurality of connecting prongs. Each prong includes a tapered head portion and a peripherally extending top locking ridge. A bottom locking ridge is separated from the top locking ridge by an upper recess. A substrate ridge is disposed at the base of each prong just above the substrate. A lower recess separates the substrate ridge from the bottom locking ridge. The dimensions of the prongs are such that adjacent prongs form a cavity corresponding in shape to the prongs of a matching fastener.
U.S. Pat. No. 3,266,113 of W. C. Flanagan, Jr., issued Aug. 16, 1966, discloses in FIGS. 6, 6A, 6B interlocking articles having enlarged heads and a ridge on the stems of the articles. The heads are retained between the ridges and sockets formed in the base or substrate of the articles. The article can be moved with relative ease from shallow to deep engagement by moving the heads past the ridges, but can be disengaged completely from one another only with application of a greater force. Other types of interlocking articles are also disclosed by this patent.
The foregoing discussed patents should be carefully considered in order to put the present invention into proper perspective. An object of the present invention is to provide an improved mechanical fastener that is strong in the sense that it is relatively difficult to separate the interlocking fastener, yet which is relatively flexible in a planar direction to provide some give between the fastener elements.